tuenti2.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Tuenti2
{
    class Program
    {
        class Node
        {
            public char Content { get; set; }
            public int Appearances { get; set; }
            public Node Parent { get; set; }
            public List<Node> Children { get; set; }

            public string ToWord()
            {
                var current = this;
                var word = "";

                while (current != null)
                {
                    if (current.Content != ' ')
                        word = current.Content + word;
                    current = current.Parent;
                }

                word += " " + Appearances.ToString();

                return word;
            }
        }

        private static Node _first = null;
        private static Node _second = null;
        private static Node _third = null;

        static void Main(string[] args)
        {
            var corpus = File.ReadAllText("corpus.txt");
            var words = corpus.Split(new char[] { ' ' }, StringSplitOptions.RemoveEmptyEntries);

            var lines = File.ReadAllLines("submitInput.txt");
            var n = Convert.ToInt32(lines[0]);

            var result = "";
            for (int i = 1; i <= n; i++)
            {   
                var firstIndex = Convert.ToInt32(lines[i].Split(' ')[0]) - 1;
                var lastIndex = Convert.ToInt32(lines[i].Split(' ')[1]) - 1;
                var root = new Node { Content = ' ', Appearances = 0 };

                for (int j = firstIndex; j <= lastIndex; j++)
                {
                    AddWord(root, words[j], 0);
                }

                UpdateRank(root);

                result += string.Format("Case #{0}: {1},{2},{3}\n", i, _first.ToWord(), _second.ToWord(), _third.ToWord());
                _first = null;
                _second = null;
                _third = null;
            }

            File.WriteAllText("submitOutput.txt", result);
        }

        static void UpdateRank(Node n)
        {
            if (n.Children == null) 
            {
                if (_first == null) _first = n;
                else
                {
                    if (_first.Appearances < n.Appearances)
                    {
                        _third = _second;
                        _second = _first;
                        _first = n;
                    }
                    else
                    {
                        if (_second == null)
                            _second = n;
                        else
                        {
                            if (_second.Appearances < n.Appearances)
                            {
                                _third = _second;
                                _second = n;
                            }
                            else
                            {
                                if (_third == null || _third.Appearances < n.Appearances)
                                    _third = n;
                            }
                        }
                    }
                }
            }
            else
            {
                foreach (var child in n.Children)
                {
                    UpdateRank(child);
                }
            }
        }

        static void AddWord(Node node, string word, int pointer)
        {
            if (pointer >= word.Length) return;
            else
            {
                if (node.Children == null)
                {
                    var newNode = new Node { Content = word[pointer], Appearances = (pointer == word.Length - 1) ? 1 : 0, Parent = node };
                    node.Children = new List<Node>();
                    node.Children.Add(newNode);
                    pointer++;
                    AddWord(newNode, word, pointer);
                }
                else
                {
                    Node foundChild = null;
                    foreach (var child in node.Children)
                    {
                        if (child.Content == word[pointer])
                        {
                            foundChild = child;
                            break;
                        }    
                    }

                    if (foundChild != null)
                    {
                        if (pointer == word.Length - 1)
                            foundChild.Appearances++;
                        else
                        {
                            pointer++;
                            AddWord(foundChild, word, pointer);
                        }
                            
                    }
                    else
                    {
                        var newNode = new Node { Content = word[pointer], Appearances = (pointer == word.Length - 1) ? 1 : 0, Parent = node };

                        node.Children.Add(newNode);
                        pointer++;
                        AddWord(newNode, word, pointer);
                    }
                }
            }
        }
    }
}